Kano , Nigeria -LRB- CNN -RRB- -- Residents of Kano in Nigeria are struggling to keep alive their centuries-old tradition of hand-dying delicate cloth a deep indigo blue , with their trade under threat from the realities of modern commerce .

Kano 's pits are said to date back 500 years and were once the center of a bustling Saharan trade in dyed cloth .

There are still over 120 pits in Kano but only 30 of them are functioning . Many of them have been filled in , often because families have moved on to other businesses , but sometimes because they 're waiting for their children to grown up , dig out the pit and reclaim their tradition .

Sixty-five-year-old Yusuf Abdu has worked in the dye pits since he was a boy . The pits are family owned and Abdu has trained his 21-year-old son to continue the tradition , but such dedication is rare .

`` A lot of our elders have died , so we are calling our families to come back and embrace the work again , '' said Abdu , who is hoping his son will pass on the knowledge to another generation .

Indigo , potassium and ash are mixed with water in the pits , and then the cloth soaked for up to six hours . The longer it 's soaked , the deeper the color .

`` We are using the same ways dyers used when the pits began in 1498 , '' explained Abdu .

`` We can not use modern methods because that will change our tradition . ''

Methods of ironing the cloth are just as traditional ; material is beaten with a mallet to remove creases . But these ancient production lines are now being hammered by competition from cheaper foreign fabrics and the rising costs of energy and materials at home .

`` There have been a lot of changes . Materials that once cost $ 10 now cost $ 40 , '' said Abdu .

Despite its rich history , regional demand for the dyed wares has fallen as fashions have changed , so the dyers are looking to tourists as potential buyers .

Abdu hopes that with their custom the dye trade will continue , as it has for centuries , and that one day his son will be passing on the traditional techniques to his grandson .

@highlight

Kano is said to be home to the oldest dye pits in Africa , dating back to 1498

@highlight

Indigo , potassium and ash are mixed with water to produce a deep blue dye

@highlight

The tradition is under threat from cheap fabric imports from abroad